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Bacteria are often present in the mouth of cattle. As a result, anything puncturing the mouth tissue can open the way for infection, which can lead to "lump jaw."

According to Salmon, ID, veterinarian Robert Cope, there are two kinds of lump jaw. Each is caused by two different types of bacteria and require different treatment.

The most common are soft tissue infections that are relatively easy to treat. Sometimes, these abscesses break and drain on their own. Usually, however, they must be lanced, drained and disinfected before they'll heal properly.

Another type of lump jaw is caused by infection in the bone, and it's difficult to halt, Cope says. Usually, it results in having to sell or butcher the animal.

Bony lump jaw tends to occur in two- to three-year-old cattle, says Pete South, a retired veterinarian and professor at University of Idaho.

A Common Beginning

Both forms of lump jaw actually begin in the same manner, says Cope. A break in the tissue surface allows bacteria to enter - which can happen if a cow eats or chews on a sharp stick or even a pointed blade of stiff grass. A sharp seed may poke into the side of the mouth. Ulcers caused by BVD virus can open the way for bacteria, which can then enter from feed or soil.

Ingesting dirt can also play a part, introducing certain bacteria that can begin an infection if there's a break in the tissues.

The soft tissue variety

The most common form of lump jaw is caused by Actinobacillus bacteria. It occurs in the soft tissues, forming an abscess, often along the lower jaw.

"Actinobacillus is a gram-negative bacteria routinely present in soil," says Cope. "Once the bacteria enter the mouth tissues they immediately begin to grow and stimulate an inflammatory response from the cow, resulting in formation of an abscess."

Treating with an injectable antibiotic generally isn't useful, Cope says. The abscess is a pocket of infection surrounded by a relatively thick wall of connective tissue. This wall prevents the infection from spreading through the body, but also keeps antibiotics in the blood stream from reaching the infective organism.

The best treatment is to lance the abscess and flush it out with strong (7%) iodine, he says. One or two treatments will usually suffice to cure the problem. He recommends waiting until the infection comes to a head with a soft spot in the lump. If you lance it too early, it will not yet have formed a drainable pus pocket.

The lump may be either hard or soft, but moves if pressed firmly with your hand, he says. It's not attached to the bone. Inserting a needle (16 ga. or larger) into the lump is another diagnostic check. If it's an abscess, pus will come out the needle or be present in the needle when you remove it.

If pus is present, lance the abscess at its lowest point (with scalpel or sharp knife) to allow drainage. After squeezing out the pus, flush the abscess with tincture of iodine (7% solution) to remove the rest.

This type of abscess usually heals quickly once it's opened and drained, unless the drain hole seals over before all infection is out. Then, it must be opened and flushed again.